The overall objective of this behavioral research project is to determine the extent to which sucrose displaces nutrients in the diet of preschool children and promotes the disruption of protein-energy intake regulation. Previous research in this area has yielded the finding that preschool children consume enormous quantities of a highly palatable beverage when it is offered in a meal, without decreasing their intake of other food items in the meal, consuming a mean of 25% more calories when offered chocolate milk with their meals than when offered plain milk. The research proposed here would attempt to explain this failure in self-regulatory eating, plus test the effects of sucrose on snack and meal eating by preschool children. The design of this study involves serving lunch and a morning and afternoon snack two days a week for twelve weeks to 120 preschool children, either in daycare centers (N = 80) or in private homes (N = 40). Four meals on a rotating menu will be used. Subjects will be offered each meal six times during the twelve week period, twice with each of the three test beverages, plain milk, chocolate sucrose-sweetened milk, and chocolate aspartame-flavored milk. Undergraduate research assistants will transport the lunches to the subjects, record the order of food items consumed and the amount of time spent eating each item, and measure the amount of food and beverages consumed during lunch and snacks. The emphasis of the data analysis will be behavioral, rather than nutritional. It is expected that the findings will provide a baseline of normative eating by healthy, preschool children against which the eating behavior of seriously ill children can be compared. These findings would have important implications for the role of sucrose in the development of childhood obesity.